The Norwegian midfielder, 23, joined the Scottish champions from Stromgodset last week on a three-and-a-half-year deal.
Despite having only been at the club for a matter of days, Commons is hopeful that Johansen can improve the side.
"He's trained with us twice now and he looks like a very good player, technically very good," he told Celtic's official website.
"He's got a good left foot and I heard him say in his interviews that he enjoys a passing game, and likes to look for through balls, so hopefully he will add something to the side and help us kick on."
Celtic continue the defence of their Scottish Premiership title on Sunday when they travel to Hibernian.